Because most of the popular series are already tied up in exclusive licensing agreements with someone else, and if you want the publisher to reconsider the exclusive agreement with your competitor when it comes time to renew the license, then you have to have a lot of power to overcome the relationship between the licensor and licensee, especially in Japan.
Licensing does cost the producers (once again, especially in Japan) when they are not super organized, and have to source the materials for delivery, and dedicate manpower to checking the contracts.
Suppose that there is no exclusive licensing deal and that it's just that they can't be bothered to source the material. What if you offer to source the material yourself through alternative means, say by ripping them from aggregators? So that licensing for them only means checking a contract and giving you an ok. Would that help?
Why? What's the downside of licensing content to smaller publishers? Licensing doesn't cost the producers anything right?